var banner = new Array(1);

banner[0]='https://i264.photobucket.com/albums/ii188/Astram128/Forums/IPG2.png';
banner[1]='https://i264.photobucket.com/albums/ii188/Astram128/Forums/IPBan1.png';

document.getElementById('i_logo').src= banner[Math.floor(Math.random(1)*banner.length)];